Phase transformation in mechanically alloyed and hot-pressed Nb-4Si-8B and Nb-8Si-16B alloys

• Autor(a) principal: Chiaradia, Carlos Edilson [UNESP]
• Data de Publicação: 2014
• Outros Autores: Alkmin, Luciano Braga, Nunes, Carlos ÂNgelo, Henriques, André Rodrigues ViníCius, Maria Cortez Pereira, Gilda [UNESP], Ramos, Alfeu Saraiva [UNESP]
• Tipo de documento: Artigo de conferência
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.4028/www.scientific.net/MSF.802.14; http://hdl.handle.net/11449/227921
• topic: Contamination; High-energy ball milling; Hot pressing; Niobium alloys

The work reports on the phase transformation in mechanically alloyed and hot-pressed Nb-4Si-8B and Nb-8Si-16B (at-%) alloys. Elemental powder mixtures were processed in a planetary ball mill under argon atmosphere using 300 rpm, stainless steel balls (19 mm diameter) and vials (225 mL), and a ball-to-powder weight ratio of 10:1. After dry milling for 7h, wet milling with isopropyl alcohol for more 20 min was adopted to increase the recovering of previously coldwelded Nb-4Si-8B powders. To obtain the equilibrium structures the as-milled powders were hotpressed under vacuum at 1200oC for 1 h. The as-milled powders and hot-pressed samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. XRD results revealed the presence of metastable phases in as-milled Nb-Si-B powders. The hot pressing has produced dense Nb-Si-B samples, which were formed by the Nbss, Nb3B2and Fe2Nb phases beside of other unknown Si-rich phase.